Executing functions with keyword-only arguments raises an errorr

[lesteve]

Related joblib bug: joblib/joblib#863

from loky import get_reusable_executor


def func_with_kw_only_args(a, *, b=1):
    return a + b


executor = get_reusable_executor(max_workers=2)

res = executor.submit(func_with_kw_only_args, 1)
print("Got results:", res.result())

Traceback:

---------------------------------------------------------------------------
_RemoteTraceback                          Traceback (most recent call last)
_RemoteTraceback: 
"""
Traceback (most recent call last):
  File "/home/local/lesteve/dev/loky/loky/process_executor.py", line 418, in _process_worker
    r = call_item()
  File "/home/local/lesteve/dev/loky/loky/process_executor.py", line 272, in __call__
    return self.fn(*self.args, **self.kwargs)
TypeError: func_with_kw_only_args() missing 1 required keyword-only argument: 'b'
"""

The above exception was the direct cause of the following exception:

TypeError                                 Traceback (most recent call last)
<ipython-input-12-ec20eabd887b> in <module>
      9 
     10 res = executor.submit(func_with_kw_only_args, 1)
---> 11 print("Got results:", res.result())
     12 

/home/local/lesteve/miniconda3/lib/python3.7/concurrent/futures/_base.py in result(self, timeout)
    430                 raise CancelledError()
    431             elif self._state == FINISHED:
--> 432                 return self.__get_result()
    433             else:
    434                 raise TimeoutError()

/home/local/lesteve/miniconda3/lib/python3.7/concurrent/futures/_base.py in __get_result(self)
    382     def __get_result(self):
    383         if self._exception:
--> 384             raise self._exception
    385         else:
    386             return self._result

TypeError: func_with_kw_only_args() missing 1 required keyword-only argument: 'b'

[lesteve]

Note: putting the function with keyword-only arguments in a module works, so I am guessing the bug lies in the magic to pickle the __main__ namespace.

[lesteve]

I opened a bug in cloudpickle since this is very likely where the root problem lies: cloudpipe/cloudpickle#263

[ogrisel]

cloudpipe/cloudpickle#264 was merged and released in cloudpickle 1.2.0, so I assume this can be closed as well.